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'''''Panicum virgatum''''', commonly known as '''switchgrass''', is a warm season [[grass]] and is one of the dominant [[species]] of the central [[North America]]n [[tallgrass prairie]]. It can be found in remnant prairies, along roadsides, [[pasture]]s and as an [[ornamental plant]] in [[garden]]s. Other common names for it include '''tall panic grass''', '''Wobsqua grass''', '''blackbent''', '''tall prairiegrass''', '''wild [[Agrostis|redtop]]''' and '''thatchgrass'''. In his [[2006 State of the Union Address]], U.S. President [[George W. Bush]] touted switchgrass as a non-food, low-carbon raw material for biofuels that could reduce the USA's dependence on [[petroleum]].
'''''Panicum virgatum''''', commonly known as '''switchgrass''', is a perennial warm season [[grass]] native to North America, where it occurs naturally from 55° N latitude in [[Canada]] southwards into the [[United States]] and [[Mexico]]. Switchgrass is one of the dominant [[species]] of the central [[North America]]n [[tallgrass prairie]] and can be found in remnant [[prairie]]s, in native grass [[pasture]]s, and naturalized along roadsides. It is used primarily for [[soil conservation]], [[forage]] production, game cover, as an [[ornamental grass]], and more recently as a [[biomass]] crop for [[ethanol]], fibre, electricity, and heat production. Other common names for switchgrass include '''tall panic grass''', '''Wobsqua grass''', '''blackbent''', '''tall prairiegrass''', '''wild [[Agrostis|redtop]]''' and '''thatchgrass'''.


==Properties==
==Properties==

Revision as of 20:11, 13 February 2009

Switchgrass
Scientific classification
Kingdom:
Plantae
(unranked):
Angiosperms
(unranked):
Monocots
(unranked):
Commelinids
Order:
Poales
Family:
Poaceae
Genus:
Panicum
Species:
P. virgatum
Binomial name
Panicum virgatum

Panicum virgatum, commonly known as switchgrass, is a perennial warm season grass native to North America, where it occurs naturally from 55° N latitude in Canada southwards into the United States and Mexico. Switchgrass is one of the dominant species of the central North American tallgrass prairie and can be found in remnant prairies, in native grass pastures, and naturalized along roadsides. It is used primarily for soil conservation, forage production, game cover, as an ornamental grass, and more recently as a biomass crop for ethanol, fibre, electricity, and heat production. Other common names for switchgrass include tall panic grass, Wobsqua grass, blackbent, tall prairiegrass, wild redtop and thatchgrass.

Properties

Root system of switchgrass grown at The Land Institute

Switchgrass is a hardy, deep rooted, perennial rhizomatous grass which begins growth in late spring. It can grow up to 1.8-2.2 m high but is typically shorter than Big Bluestem grass or Indiangrass. The leaves are 30-90 cm long, with a prominent midrib. Switchgrass uses C4 carbon fixation, giving it an advantage in conditions of drought and high temperature.[1] Its flowers have a well-developed panicle, often up to 60 cm long and bear a good crop of fruits. The fruits are 3-6 mm long and up to 1.5 mm wide, and are developed from a single-flowered spikelet. Both glumes are present and well developed. When ripe, the seeds sometimes take on a pink or dull-purple tinge, and turn golden brown with the foliage of the plant in the fall. Switchgrass is a self-seeding crop, which means farmers do not have to plant and re-seed after annual harvesting. Once established, a switchgrass stand can survive for ten years or longer.[2] Also, unlike corn, switchgrass can grow on marginal lands and requires little or no fertilizer to thrive.[2]

Background

Much of North America, especially the prairies of the Midwestern United States, was once prime habitat to vast swaths of native grasses including Switchgrass (Panicum virgatum), Indiangrass (Sorghastrum nutans), Eastern Gamagrass (Tripsacum dactyloides), Big Bluestem (Andropogon gerardii), Little Bluestem (Schizachyrium scoparium) and others. As European settlers began spreading west across the continent, the native grasses were displaced by large farms growing crops such as corn and wheat. Introduced grasses such as fescue, bluegrass, and orchardgrass [3] also replaced the native grasses.

Distribution

Switchgrass is a very versatile and adaptable plant. It can grow and even thrive in many weather conditions, lengths of growing seasons, soil types and land conditions. Its distribution spans south of latitude 55°N from Saskatchewan to Nova Scotia and south over most of the United States east of the Rocky Mountains.[4] As a warm season perennial grass, most of its growth occurs from late spring through early fall, becoming dormant and unproductive during colder months. Thus, the productive season in its northern habitat can be as short as three months, but in the southern reaches of its habitat, the growing season may be as long as eight months around the Gulf Coast area.[5]

Switchgrass’ suitability for cultivation in the Gran Chaco is currently studied by Argentina’s INTA [6]

Establishment

Once established, it takes three years for a stand of switchgrass to reach its full potential[7]. According to David Bransby at Auburn University, it will produce a quarter to a third of its full potential in its first year and two-thirds in its second year[8]. It is sometimes suggested that the stand not be harvested during the establishment year[7]. Afterwards, each region has its own recommendations for fertilizer rates. The timing of harvesting depends upon how the switchgrass is to be used, and weed control can be addressed with limited herbicides, controlled burns, and mechanical methods.

Uses

Switchgrass is grazed by certain animals, used as ground cover to control erosion, and farmed as forage for beef cows. Switchgrass contains natural chemical compounds, called saponins, that may cause health problems to horses, goats, sheep and other livestock.

Switchgrass is rich in cellulose, making it attractive as a source for cellulosic ethanol.[9] It is at the core of an alternative fuel strategy announced by Tennessee Governor Phil Bredesen in January 2007.[10]

As a drought resistant ornamental grass, it is easily grown in average to wet soils and in full sun to part shade. Establishment is recommended in the spring, at the same time as corn is planted.

Soil conservation

Further information: [[:Mine reclamation, Restoration ecology, and Revegetation]]

Switchgrass is useful for soil conservation and amendment, particularly in the United States and Canada where switchgrass is endemic. Switchgrass has a deep fibrous root system – nearly as deep as the plant is tall. Since it, along with other native grasses and forbs, once covered the plains of the United States that are now the Corn Belt, the effects of the past switchgrass habitat has been beneficial, lending to the fertile farmland that exists today. The deep fibrous root systems of switchgrass left a very deep rich layer of organic matter in the soils of the midwest; making those mollisol soils some of the most productive in the world. By returning switchgrass and other perennial prairie grasses as an agricultural crop, many marginal soils may benefit from increased levels of organic material, permeability, and fertility from the grass's deep root system.

Soil erosion, both from wind and water, is of great concern in regions where switchgrass grows. Due to its height, switchgrass can form an effective wind erosion barrier.[11] Its root system, also, is excellent for holding soil in place, which helps prevent erosion from flooding and runoff. Some highway departments (for example, KDOT) have used switchgrasses in their seed mixes when re-establishing growth along roadways.[12] It can also be used on strip mine sites, dikes[11], and pond dams. Conservation districts in many parts of the United States use it to control erosion in grass waterways because of its excellent ability to anchor soils while also doubling as native habitat for wildlife.

Game cover

Switchgrass is well-known among wildlife conservationists as a favorite forage and habitat among upland game bird species such as pheasant, quail, grouse, wild turkey, and song birds, with its plentiful small seeds and tall cover. Depending on how thickly switchgrass is planted, and what it is partnered with, it also offers excellent forage and cover for a wide variety of other wildlife across the country. For those producers who have switchgrass stands on their farm, it is considered an environmental and aesthetic benefit due to the abundance of wildlife attracted by the switchgrass stands. Some members of Prairie Lands Bio-Products, Inc. in Iowa have even turned this benefit into a profitable business by leasing their switchgrass land for hunting during the proper seasons.[13] The benefits to wildlife can be extended even in large scale agriculture through the process of strip harvesting as recommended by the Wildlife Society, which suggests that rather than harvesting an entire fields at once, strip harvesting could be practiced so the entire habitat is not removed thereby protecting the wildlife that has inhabited the switchgrass.[14]

Biofuel

Panicum virgatum 'Heavy Metal' switchgrass in early summer

Switchgrass is often considered a good candidate for biofuel — especially ethanol fuel — production due to its hardiness in poor soil and climate conditions, rapid growth and low fertilization and herbicide requirements. Switchgrass is also perennial, unlike corn, and has a large biomass output (the raw plant material used to make biofuel) of 6-10 tons per acre.[15][2] U.S. President George W. Bush proposed the usage of switchgrass in his 2006 State of the Union address [16] [17][18]; since then, over $100 million has been invested into researching switchgrass as a potential biofuel source[19].

Switchgrass has the potential for enough biomass to produce up to 100 gallons (380 liters) of ethanol per metric ton harvested.[20] This gives switchgrass the potential to produce 1,000 gallons of ethanol per acre, compared to 665 gallons per acre of sugarcane and 400 gallons per acre of corn.[21]

However, there is debate on the economic and environmental viability of switchgrass, and all other biofuels, as an efficient energy source. In recent studies, it has been argued that switchgrass has a negative ethanol fuel energy balance, requiring 45 percent more fossil energy to create switchgrass into a biofuel than is produced.[22] Some studies have countered these arguments, however, finding that for every unit of energy input to create a biofuel from switchgrass, four units of energy are yielded.[23] In a 2007 lecture Professor Richard Muller, of the University of California, Berkeley, noted that it is the conversion of switchgrass biomass, mainly cellulose, into ethanol which introduces significant inefficiencies. It was also noted that The Helios Project at Lawrence Berkeley Laboratory is actively trying to engineer metabolic pathways in bacteria to convert cellulose to ethanol more efficiently.

Switchgrass is being used to heat small industrial and farm buildings in Germany and China through a process used to make a low quality natural gas substitute.[2] It can also be pressed into fuel pellets which are burned in pellet stoves used to heat homes, which typically burn corn or wood pellets.[7]

In the spring of 2008, 1,000 acres (4.0 km2) of switchgrass will be planted near Guymon, Oklahoma, in the Oklahoma Panhandle to study the feasibility of using the crop for biofuel. It will be the largest stand ever planted for such purposes. The project is being spearheaded by the Oklahoma Bioenergy Center, a state project backed by Governor Brad Henry.[24]

Forages

Switchgrass is an excellent forage for cattle; however, it has shown toxicity in horses, sheep and goats[25][26][27] through chemical compounds known as saponins, which cause photosensitivity and liver damage in these animals. Researchers are continuing to learn more about the specific conditions under which the switchgrass must be in order to cause harm to these species, but until more is discovered, it is recommended that switchgrass not be fed to them. For cattle, however, it can be fed as hay, or grazed.

Grazing switchgrass calls for watchful management practices to ensure survival of the stand. It is recommended that grazing begin when there is 18 – 22 inches of growth, to stop grazing when there are 8 – 12 inches of stubble left, and to rest the pasture 30 – 45 days between grazing periods[28]. Switchgrass becomes very stemmy and unpalatable as it matures, but during the target grazing period, it is a highly favorable forage with a relative feed value (RFV) of 90-104[29]. The grass' upright growth pattern places its growing point off the soil surface onto its stem, so leaving 8 – 12 inches of stubble is important for regrowth. When harvesting switchgrass for hay, the first cutting occurs at the late boot stage – around mid-June. This should allow for a second cutting in mid-August, leaving enough regrowth to survive the winter.[30]

Seed suppliers

Agrecol Corporation

Bamert Seed Company

Blade Energy Crops

Blight Native Seeds Ltd.

Ernst Conservation Seeds

Interlake Forage Seeds

Roundstone Native Seed LLC

Rupp Seeds

Sharp Bros Seed Co.

Stock Seed Farms

See also

References

  1. ^ Silzer, Tanya (2000). "Panicum virgatum L., Switchgrass, prairie switchgrass, tall panic grass". Rangeland Ecosystems & Plants Fact Sheets. University of Saskatchewan Department of Plant Sciences. Retrieved 2007-12-08. {{cite web}}: Unknown parameter |month= ignored (help)
  2. ^ a b c d Secter, Bob. "Plentiful switch grass emerges as breakthrough biofuel". The San Diego Union-Tribune. Retrieved 2008-05-24. {{cite web}}: Text "The San Diego Union-Tribune" ignored (help)
  3. ^ Ernst Seed Catalog Web Page (2007). "Switchgrass and Warm Season Grass Planting Guide". Ernst Conservation Seeds. Retrieved 2007-12-08.
  4. ^ "PLANTS Profile for Panicum virgatum (switchgrass)". United States Department of Agriculture, Natural Resources Conservation Service. Retrieved 2008-05-21.
  5. ^ Ball, D.M. (2002). Southern Forages (3rd edition ed.). International Plant Nutrition Institute. p. 26. ISBN 0-9629598-3-9. {{cite book}}: |edition= has extra text (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
  6. ^ "Aprovechamiento de recursos vegetales y animales para la produccion de biocombustibles" (PDF) (in Spanish). INTA. 26 June 2008.
  7. ^ a b c Samson, R. (2007). "Switchgrass Production in Ontario: A Management Guide" (PDF). Resource Efficient Agricultural Production (REAP) - Canada. Retrieved 2008-05-24.
  8. ^ Bransby, David (2005). "Switchgrass Profile". Bioenergy Feedstock Information Network (BFIN), Oak Ridge National Laboratory. Retrieved 2008-05-24.
  9. ^ M. R. Schmer, K. P. Vogel, R. B. Mitchell, and R. K. Perrin (2008). "Net energy of cellulosic ethanol from switchgrass". PNAS. 105 (2): 464–469. doi:10.1073/pnas.0704767105. PMID 18180449.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  10. ^ Phil Bredesen Governor, State of Tennessee
  11. ^ a b "Plant Fact Sheet, Panicum virgatum (switchgrass)" (PDF). United States Department of Agriculture, Natural Resources Conservation Service, Plant Materials Program. 2006-05-06. Retrieved 2008-05-21.
  12. ^ "KDOT Bid Tabs". Kansas Department of Transportation. Retrieved 2008-05-20.
  13. ^ Hipple, Patricia C. (2002). "Farmers' Motivations for Adoption of Switchgrass" (PDF). In Jules Janick, Anna Whipkey (ed.). Trends in New Crops and New Uses. Fifth National Symposium, New Crops and New Uses, Strength in Diversity. Alexandria, Virginia: American Society for Horticultural Science. pp. 252–266. ISBN 0097075655. Retrieved 2008-05-23. {{cite conference}}: Cite has empty unknown parameter: |month= (help); External link in |conferenceurl= (help); Unknown parameter |booktitle= ignored (|book-title= suggested) (help); Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |conferenceurl= ignored (|conference-url= suggested) (help)
  14. ^ Bies, Laura (2006-11-01). "The Biofuels Explosion: Is Green Energy Good for Wildlife?". Wildlife Society Bulletin. 34 (4): 1203–1205. doi:10.2193/0091-7648(2006)34[1203:TBEIGE]2.0.CO;2. {{cite journal}}: |access-date= requires |url= (help)
  15. ^ bioenergy.ornl.gov "Switchgrass Profile". David Bransby, Auburn University. Retrieved 2007-01-05. {{cite web}}: Check |url= value (help)
  16. ^ Adrienne Mand Lewin (2006-02-01). "Switchgrass: The Super Plant Savior?". ABC News.
  17. ^ "Switch Grass: Alternative Energy Source?". National Public Radio. 2006-02-01.
  18. ^ Dana Bash, Suzanne Malveaux; et al. (2006-02-01). "Bush has plan to end oil 'addiction'". CNN. {{cite web}}: Explicit use of et al. in: |author= (help)
  19. ^ "Since that mention in the 2006, investment in switch grass has exploded, thanks in large part, experts say, to the president's speech. Venture capitalists have poured over $100 million dollars into private companies that are exploring the technology necessary to convert switchgrass into fuel, and large publicly-owned companies are also directing their research dollars into biofuels."Jessica Yellin, Katie Hinman, Nitya Venkataraman (2007-01-23). "What Happened to Bush Call for Switchgrass?". ABC News.{{cite web}}: CS1 maint: multiple names: authors list (link)
  20. ^ "Switchgrass: Native American Powerhouse?". Renewable Energy Resources. Retrieved 2007-01-05.
  21. ^ "Biomass Energy: Growing Crops For Fuel". Texas State Energy Conservation Office. Retrieved 2007-01-05.
  22. ^ "Ethanol And Biodiesel From Crops Not Worth The Energy". ScienceDaily. Retrieved 2007-01-05.
  23. ^ "Switch Grass: Alternative Energy Source?". NPR. Retrieved 2007-01-05.
  24. ^ Oklahoma to plant largest stand of switchgrass ever for fuel research | Farm and Dairy - The Auction Guide and Rural Marketplace
  25. ^ Lee, S.T. (2001). "The isolation and identification of steroidal sapogenins in switchgrass". J Nat Toxins. 10 (4): 273–81. Retrieved 2008-05-24. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  26. ^ Johnson, A.L. (2006). "Fall Panicum (Panicum dichotomiflorum) Hepatotoxicosis in Horses and Sheep". Journal of Veterinary Internal Medicine. 20 (6): 1414–1421. doi:10.1892/0891-6640(2006)20[1414:FPPDHI]2.0.CO;2. Retrieved 2008-05-24. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  27. ^ Stegelmeier, B.L. (2007). "Switchgrass (panicum Virgatum) Toxicity In Rodents, Sheep, Goats And Horses". Poisonous Plant Global Research and Solutions. 19: 113–117. Retrieved 2008-05-24. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  28. ^ Ball, D.M. (2006). "Table 28. Guidelines for rotational stocking of selected forage crops". Forage Crop Pocket Guide. International Plant Nutrition Institute. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  29. ^ Ball, D.M. (2006). "Table 33b. Total Digestible Nutrients (TDN) and Relative Feed Value (RFV) Ranges for Various Forage Crops". Forage Crop Pocket Guide. International Plant Nutrition Institute. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  30. ^ Wolf, D.D. (1995). "Planting and managing switchgrass for forage, wildlife, and conservation" (PDF). Virginia Cooperative Extension Publication: 418–013. Retrieved 2008-05-24. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

External links

Retrieved from "https://en.wikipedia.org/w/index.php?title=Panicum_virgatum&oldid=270512769"